Touch screen with sensory feedback

ABSTRACT

A load control device for controlling the amount of power delivered to an electrical load from an AC power source provides improved sensory feedback to a user of the load control device. The load control device comprises a touch screen actuator having a touch sensitive front surface responsive to a plurality of point actuations, each characterized by a position and a force. The touch screen actuator has an output operatively coupled to a controller for providing a control signal representative of the position of the point actuation. The load control device further comprises a visual display and an audible sound generator, both responsive to the controller. The controller is operable to cause the visual display to illuminate and the audible sound generator to generate an audible sound in response to the control signal of the touch screen actuator.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to load control devices for controllingthe amount of power delivered to an electrical load from a power source.More specifically, the present invention relates to a touch dimmerhaving a touch sensitive device.

2. Description of the Related Art

A conventional two-wire dimmer has two terminals: a “hot” terminal forconnection to an alternating-current (AC) power supply and a “dimmedhot” terminal for connection to a lighting load. Standard dimmers useone or more semiconductor switches, such as triacs or field effecttransistors (FETs), to control the current delivered to the lightingload and thus to control the intensity of the light. The semiconductorswitches are typically coupled between the hot and dimmed hot terminalsof the dimmer.

Smart wall-mounted dimmers include a user interface typically having aplurality of buttons for receiving inputs from a user and a plurality ofstatus indicators for providing feedback to the user. These smartdimmers typically include a microcontroller or other processing devicefor providing an advanced set of control features and feedback optionsto the end user. An example of a smart dimmer is described in greaterdetail in commonly assigned U.S. Pat. No. 5,248,919, issued on Sep. 28,1993, entitled LIGHTING CONTROL DEVICE, which is herein incorporated byreference in its entirety.

FIG. 1 is a front view of a user interface of a prior art smart dimmerswitch 10 for controlling the amount of power delivered from a source ofAC power to a lighting load. As shown, the dimmer switch 10 includes afaceplate 12, a bezel 14, an intensity selection actuator 16 forselecting a desired level of light intensity of a lighting load (notshown) controlled by the dimmer switch 10, and a control switch actuator18. Actuation of the upper portion 16A of the intensity selectionactuator 16 increases or raises the light intensity of the lightingload, while actuation of the lower portion 16B of the intensityselection actuator 16 decreases or lowers the light intensity. Theintensity selection actuator 16 may control a rocker switch, twoseparate push switches, or the like. The control switch actuator 18 maycontrol a push switch or any other suitable type of actuator andtypically provides tactile and auditory feedback to a user when pressed.

The smart dimmer 10 also includes an intensity level indicator in theform of a plurality of light sources 20, such as light-emitting diodes(LEDs). Light sources 20 may be arranged in an array (such as a lineararray as shown) representative of a range of light intensity levels ofthe lighting load being controlled. The intensity level of the lightingload may range from a minimum intensity level, which is preferably thelowest visible intensity, but which may be zero, or “full off,” to amaximum intensity level, which is typically “full on.” Light intensitylevel is typically expressed as a percentage of full intensity. Thus,when the lighting load is on, light intensity level may range from 1% to100%.

By illuminating a selected one of the light sources 20 depending uponlight intensity level, the position of the illuminated light sourcewithin the array provides a visual indication of the light intensityrelative to the range when the lamp or lamps being controlled are on.For example, seven LEDs are illustrated in FIG. 1. Illuminating theuppermost LED in the array will give an indication that the lightintensity level is at or near maximum. Illuminating the center LED willgive an indication that the light intensity level is at about themidpoint of the range. In addition, when the lamp or lamps beingcontrolled are off, all of the light sources 18 are illuminated at a lowlevel of illumination, while the LED representative of the presentintensity level in the on state is illuminated at a higher illuminationlevel. This enables the light source array to be more readily perceivedby the eye in a darkened environment, which assists a user in locatingthe switch in a dark room, for example, in order to actuate the switchto control the lights in the room, and provides sufficient contrastbetween the level-indicating LED and the remaining LEDs to enable a userto perceive the relative intensity level at a glance.

Touch dimmers (or “zip” dimmers) are known in the art. A touch dimmergenerally includes a touch-operated input device, such as a resistive ora capacitive touch pad. The touch-operated device responds to the forceand position of a point actuation on the surface of the device and inturn controls the semiconductor switches of the dimmer. An example of atouch dimmer is described in greater detail in commonly-assigned U.S.Pat. No. 5,196,782, issued Mar. 23, 1993, entitled TOUCH-OPERATED POWERCONTROL, the entire disclosure of which is hereby incorporated byreference.

FIG. 2 is a cross-sectional view of a prior art touch-operated device30, specifically, a membrane voltage divider. A conductive element 32and a resistive element 34 are co-extensively supported in closeproximity by a spacing frame 36. An input voltage, V_(IN), is appliedacross the resistive element 34 to provide a voltage gradient across itssurface. When pressure is applied at a point 38 along the conductiveelement 32 (by a finger or the like), the conductive element flexesdownward and electrically contacts a corresponding point along thesurface of the resistive element 34, providing an output voltage,V_(OUT), whose value is between the input voltage VIN and ground. Whenpressure is released, the conductive element 32 recovers its originalshape and becomes electrically isolated from the resistive element 34.The touch-operated device 30 is characterized by a contact resistanceR_(CONTACT) between the conductive element 32 and the resistive element34. The contact resistance R_(CONTACT) is dependent upon the force ofthe actuation of the touch-operated device 30 and is typicallysubstantially small for a normal actuation force.

FIG. 3 is a perspective view of a user interface of a prior art touchdimmer 40. The dimmer 40 comprises a touch-operated device 30, which islocated directly behind a faceplate 42. The faceplate 42 includes aflexible area 44 located directly above the conductive element 32 of thetouch-operated device 30 to permit a user to actuate the touch-operateddevice through the faceplate 42. A conventional phase-control dimmingcircuit is located within an enclosure 46 and controls the power from asource to a load in accordance with pressure applied to a selectablepoint on flexible area 44. The faceplate 42 may include optionalmarkings 48, 50, 52 to indicate, respectively, the location of flexiblearea 44, the lowest achievable intensity level of the load, and locationof a “power off” control. An optional LED array 54 provides a visualindication of intensity level of the load. When the load is a lightsource, there is preferably a linear relationship between the number ofilluminated LEDs and the corresponding perceived light level. Theflexible area 44 may optionally include a light transmissive areathrough which LED array 54 is visible.

Typical touch-operated devices 30 do not provide auditory or tactilefeedback, such as is provided by the control switch actuator 18 of theprior art dimmer 10. When a user actuates the operational area, e.g.,the flexible area 44 of the touch dimmer 40, it is desirable to providesome sort of sensory feedback to the user to inform the user that thedimmer 40 has received the input. Some prior art touch dimmers haveprovided visual feedback, e.g., the LED array 54, and auditory feedbackvia a speaker. However, prior art touch dimmers have suffered from notbeing able to provide an acceptable amount of sensory feedback to theuser. Therefore, there is a need for a touch dimmer that provides animproved sensory feedback to a user in response an actuation of theoperational area.

SUMMARY OF THE INVENTION

According to the present invention, a load control device forcontrolling the amount of power delivered to an electrical load from anAC power source comprises a semiconductor switch, a controller, a touchscreen actuator, a visual display, and an audible sound generator. Thesemiconductor switch is operable to be coupled in series electricalconnection between the source and the load. The semiconductor switch hasa control input for controlling the semiconductor switch between anon-conductive state and a conductive state. The controller isoperatively coupled to the control input of the semiconductor switch forcontrolling the semiconductor switch between the non-conductive stateand the conductive state. The touch screen actuator has a touchsensitive front surface responsive to a plurality of point actuations.Each point actuation is characterized by a position and a force. Thetouch screen actuator has an output operatively coupled to thecontroller for providing a control signal representative of the positionof the point actuation. The visual display and the audible soundgenerator are both responsive to the controller. The controller isoperable to cause the visual display to illuminate and the audible soundgenerator to generate an audible sound in response to the control signalof the touch screen actuator.

According to a second embodiment of the present invention, A loadcontrol device for controlling the amount of power delivered to anelectrical load from an AC power source comprises: a semiconductorswitch operable to be coupled in series electrical connection betweenthe source and the load, the semiconductor switch having a control inputfor controlling the semiconductor switch between a non-conductive stateand a conductive state; a controller operatively coupled to the controlinput of the semiconductor switch for controlling the semiconductorswitch between the non-conductive state and the conductive state; atouch screen actuator having a touch sensitive front surface responsiveto a plurality of point actuations, each characterized by a position anda force, the touch screen actuator having an output operatively coupledto the controller for providing a first control signal in response to afirst point actuation and a second control signal in response to asecond point actuation; and an audible sound generator responsive to thecontroller. The controller is operable to cause the audible soundgenerator to generate a first audible sound in response to the firstcontrol signal and a second audible sound in response to the secondcontrol signal.

According to a third embodiment of the present invention, a load controldevice for controlling the amount of power delivered to an electricalload from an AC power source device comprises: a semiconductor switchoperable to be coupled in series electrical connection between thesource and the load, the semiconductor switch having a control input forcontrolling the semiconductor switch between a non-conductive state anda conductive state; a controller operatively coupled to the controlinput of the semiconductor switch for controlling the semiconductorswitch between the non-conductive state and the conductive state; atouch screen actuator having a touch sensitive front surface responsiveto a plurality of point actuations, each characterized by a position anda force, the touch screen actuator operable to begin providing a controlsignal to the controller when the magnitude of the force of each of thepoint actuations exceeds substantially a minimum magnitude and to ceaseproviding the control signal when the magnitude of the forcesubsequently decreases below substantially the minimum magnitude of thepoint actuation; and an audible sound generator responsive to thecontroller. The controller is operable to cause the audible soundgenerator to generate a first audible sound in response to the controlsignal when the magnitude of the force of each of the point actuationsexceeds substantially the minimum magnitude, and to generate a secondaudible sound in response to the control signal when the magnitude ofthe force subsequently decreases below substantially the minimummagnitude of the point actuation.

Other features and advantages of the present invention will becomeapparent from the following description of the invention that refers tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a user interface of a prior art dimmer;

FIG. 2 is a cross-sectional view of a prior art touch-operated device;

FIG. 3 is a perspective view of a user interface of a prior art touchdimmer;

FIG. 4A is a perspective view of a touch dimmer according to the presentinvention;

FIG. 4B is a front view of the touch dimmer of FIG. 4A;

FIG. 5A is a partial assembled sectional view of a bezel and the touchsensitive device of the touch dimmer of FIG. 4A;

FIG. 5B is a partial exploded sectional view of the bezel and the touchsensitive device of FIG. 5A;

FIG. 6 shows the force profiles of the components and a cumulative forceprofile of the touch dimmer of FIG. 4A;

FIG. 7 is a simplified block diagram of the touch dimmer of FIG. 4A;

FIG. 8 is a simplified schematic diagram of a stabilizing circuit and ausage detection circuit of the touch dimmer of FIG. 7 according to afirst embodiment of the present invention;

FIG. 9 is a simplified schematic diagram of an audible sound generatorof the touch dimmer of FIG. 7;

FIG. 10 is a flowchart of a touch dimmer procedure executed by acontroller of the dimmer of FIG. 4A;

FIG. 11 is a flowchart of an Idle procedure of the touch dimmerprocedure of FIG. 10;

FIGS. 12A and 12B are flowcharts of an ActiveHold procedure of the touchdimmer procedure of FIG. 10;

FIG. 13 is a flowchart of a Release procedure of the touch dimmerprocedure of FIG. 10;

FIGS. 14A and 14B are flowcharts of an ActiveHold procedure forgenerating a first sound and a second sound in response to a toggleevent and a change intensity event, respectively;

FIG. 14C is a flowchart of a Release procedure that includes anadditional step for causing the audible sound generator to create arelease sound;

FIGS. 15A and 15B are simplified schematic diagrams of the circuitry fora four wire touch sensitive device and a controller of the touch dimmerof FIG. 4A according to a second embodiment of the present invention;

FIG. 15C is a simplified schematic diagram of the circuitry for a fourwire touch sensitive device and a controller of the touch dimmer of FIG.4A according to a third embodiment of the present invention;

FIG. 16A is a perspective view of a touch dimmer according to a fourthembodiment of the present invention;

FIG. 16B is a front view of the touch dimmer of FIG. 16A;

FIG. 17A is a bottom cross-sectional view of the touch dimmer of FIG.16B;

FIG. 17B is an enlarged partial view of the bottom cross-sectional viewof FIG. 17A;

FIG. 18A is a left side cross-sectional view of the touch dimmer of FIG.16B;

FIG. 18B is an enlarged partial view of the left side cross-sectionalview FIG. 18A;

FIG. 19 is a perspective view of a display printed circuit board of thedimmer of FIG. 16A;

FIG. 20 is an enlarged partial bottom cross-sectional view of a thintouch sensitive actuator according to a fifth embodiment of the presentinvention;

FIG. 21A is a perspecitive view of a touch dimmer according to a sixthembodiment of the present invention;

FIG. 21B is an enlarged right side view of the touch dimmer of FIG. 21A;and

FIG. 22 is a front view of a touch dimmer according to a seventhembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing summary, as well as the following detailed description ofthe preferred embodiments, is better understood when read in conjunctionwith the appended drawings. For the purposes of illustrating theinvention, there is shown in the drawings an embodiment that ispresently preferred, in which like numerals represent similar partsthroughout the several views of the drawings, it being understood,however, that the invention is not limited to the specific methods andinstrumentalities disclosed.

FIGS. 4A and 4B are a perspective view and a front view, respectively,of a touch dimmer 100 according to the present invention. The dimmer 100includes a faceplate 102, i.e., a cover plate, having a planar frontsurface 103 and an opening 104. The opening 104 may define a standardindustry-defined opening, such as a traditional opening or a decoratoropening, or another uniquely-sized opening as shown in FIG. 4A. A bezel106 having a planar touch sensitive front surface 108 extends throughthe opening 104 of the faceplate 102. The front surface 108 of the bezel106 is positioned immediately above a touch sensitive device 110 (shownin FIGS. 5A and 5B), i.e., a touch sensitive element, such that a userof the dimmer 100 actuates the touch sensitive element 110 by pressingthe front surface 108 of the bezel 106. As shown in FIG. 4A, the frontsurface 108 of the bezel 106 is substantially flush with the frontsurface 103 of the faceplate 102, i.e., the plane of the front surface108 of the bezel 106 is coplanar with the plane of the front surface 103of the faceplate 102. However, the bezel 106 may extend through theopening 104 of the faceplate 102 such that the front surface 108 of thebezel is provided in a plane above the plane of the front surface 103 ofthe faceplate 102. The faceplate 102 is connected to an adapter 109,which is connected to a yoke (not shown). The yoke is adapted to mountthe dimmer 100 to a standard electrical wallbox.

The dimmer 100 further comprises a visual display, e.g., a plurality ofstatus markers 112 provided in a linear array along an edge of the frontsurface 108 of the bezel 106. The status markers 112 are preferablyilluminated from behind by status indicators 114, e.g., light-emittingdiodes (LEDs), located internal to the dimmer 100 (see FIG. 7). Thedimmer 100 preferably comprises a light pipe (not shown) having aplurality of light conductors to conduct the light from the statusindicators 114 inside the dimmer to the markers 112 on the front surface108 of the bezel 106. The status indicators 114 behind the markers 112are preferably blue. As shown in FIGS. 4A and 4B, the dimmer 100comprises seven (7) status markers 112. However, the dimmer 100 maycomprise any number of status markers. Further, the status markers 112may be disposed in a vertical linear array along the center of the frontsurface 108 of the bezel 106. The markers 112 may comprise shadowsapparent on the front surface 108 due to voids behind the front surface.

The front surface 108 of the bezel 106 further includes an icon 116. Theicon 116 may be any sort of visual marker, such as, for example, a dot.Upon actuation of the lower portion of the front surface 108 surroundingthe icon 116, the dimmer 100 causes a connected lighting load 208 (FIG.7) to change from on to off (and vice versa), i.e., to toggle.Preferably, a blue status indicator and an orange status indicator arelocated immediately behind the icon 116, such that the icon 116 isilluminated with blue light when the lighting load 208 is on andilluminated with orange light when the lighting load is off. Actuationof the upper portion of the front surface 108, i.e., above the portionsurrounding the icon 116, causes the intensity of the lighting load 208to change. The status indicators 114 behind the status markers 112 areilluminated to display the intensity of the lighting load 208. Forexample, if the lighting load 208 is at 50% lighting intensity, themiddle status indicator will be illuminated. Preferably, the dimmer 100does not respond to actuations in a keepout region 118 of the frontsurface 108. The keepout region 118 prevents inadvertent actuation of anundesired portion of the front surface 108 during operation of thedimmer 100.

The dimmer 100 further includes an airgap switch actuator 119. Pullingthe airgap switch actuator 119 opens a mechanical airgap switch 219(FIG. 7) inside the dimmer 100 and disconnects the lighting load 208from a connected AC voltage source 204 (FIG. 7). The airgap switchactuator 119 extends only sufficiently above the front surface 103 ofthe faceplate 102 to be gripped by a fingernail of a user. Theelectronic circuitry of the dimmer 100 (to be described in greaterdetail below) is mounted on a printed circuit board (PCB) (not shown).The PCB is housed in an enclosure (not shown), i.e., an enclosed volume,which is attached to the yoke of the dimmer 100.

FIG. 5A is a partial assembled sectional view and FIG. 5B is a partialexploded sectional view of the bezel 108 and the touch sensitive device110 of the dimmer 100 according to the present invention. The touchsensitive device 110 comprises, for example, a resistive divider, andoperates in a similar fashion as the touch-operated device 30 of theprior art touch dimmer 40. The touch sensitive device 110 includes aconductive element 120 and a resistive element 122 supported by aspacing frame 124. However, the touch sensitive device 110 may comprisea capacitive touch screen or any other type of touch responsive element.Such touch sensitive devices are often referred to as touch pads ortouch screens.

An elastomer 126 is received by an opening 128 in the rear surface ofthe bezel 106. The elastomer 126 is positioned between the bezel 106 andthe touch sensitive device 110, such that a press on the front surface108 of the bezel is transmitted to the conductive element 120 of thetouch sensitive device 110. Preferably, the elastomer 126 is made ofrubber and is 0.040″ thick. The elastomer 126 preferably has a durometerof 40A, but may have a durometer in the range of 20A to 80A. Theconductive element 120 and the resistive element 122 of the touchsensitive device 110 and the elastomer 126 are preferably manufacturedfrom a transparent material such that the light from the plurality ofstatus indicators 114 inside the dimmer 100 are operable to shinethrough the touch sensitive device 110 and the elastomer 126 to frontsurface 108 of the bezel 106.

The position and size of the touch sensitive device 110 is demonstratedby the dotted line in FIG. 4B. The touch sensitive device 110 has alength L₁ and a width W₁ that is larger than a length L₂ and a width W₂of the front surface 108 of the bezel 106. Accordingly, a first area A₁of the surface of touch sensitive device 110 (i.e., A₁=L₁ ·W₁) isgreater than a second area A₂ of the front surface 108 of the bezel 106(i.e., A₂=L₂ ·W₂). An orthogonal projection of the second area A₂ ontothe first area A₁ is encompassed by the first area A₁, such that a pointactuation at any point on the front surface 108 of the bezel 106 istransmitted to the conductive element 120 of the touch sensitive device110. As shown in FIGS. 4A and 4B, the length L₂ of the front surface 108of the bezel 106 is approximately four (4) times greater than the widthW₂. Preferably, the length L₂ of the front surface 108 of the bezel 106is four (4) to six (6) times greater than the width W₂. Alternatively,the front surface 108 of the bezel 106 may be provided in an opening ofa decorator-style faceplate

FIG. 6 shows the force profiles of the components of the dimmer 100shown in FIGS. 5A and 5B and a cumulative force profile for the touchsensitive device 110 of the dimmer 100. Each of the force profiles showsthe force required to actuate the touch sensitive device 110 withrespect to the position of the point actuation. The force profilerepresents the amount of force required to displace the element by agiven amount. While the force profiles in FIG. 6 are shown with respectto the widths of the components of the dimmer 100, a similar forceprofile is also provided along the length of the components.

FIG. 6( a) shows a force profile of the bezel 106. The bezel 106 hassubstantially thin sidewalls 129, e.g., 0.010″ thick, such that thebezel 106 exhibits a substantially flat force profile. FIG. 6( b) showsa force profile of the touch sensitive device 110. The force required toactuate the touch sensitive device 110 increases near the edges becauseof the spacing frames 124. FIG. 6( c) shows a force profile of theelastomer 126. The force profile of the elastomer 126 is substantiallyflat, i.e., a force at any point on the front surface of the elastomer126 will result in a substantially equal force at the correspondingpoint on the rear surface.

FIG. 6( d) is a total force profile of the touch dimmer 100. Theindividual force profiles shown in FIGS. 6( a)-6(c) are additive tocreate the total force profile. The total force profile is substantiallyflat across the second area A₂ of the front surface 108 of the bezel106. This means that a substantially equal minimum actuation forcef_(MIN) is required to actuate the touch sensitive device 110 at allpoints of the front surface 108 of the bezel 106, even around the edges.Accordingly, the dimmer 100 of the present invention provides a maximumoperational area in an opening of a faceplate, i.e., substantially allof the second area A₂ of the front surface 108 of the bezel 106, whichis an improvement over the prior art touch dimmers. The minimumactuation force f_(MIN) is substantially equal at all points on thefront surface 108 of the bezel 106. For example, the minimum actuationforce f_(MIN) may be 20 grams.

FIG. 7 is a simplified block diagram of the touch dimmer 100 accordingto the present invention. The dimmer 100 has a hot terminal 202connected to an AC voltage source 204 and a dimmed hot terminal 206connected to a lighting load 208. The dimmer 100 employs a bidirectionalsemiconductor switch 210 coupled between the hot terminal 202 and thedimmed hot terminal 206, to control the current through, and thus theintensity of, the lighting load 208. The semiconductor switch 210 has acontrol input (or gate), which is connected to a gate drive circuit 212.The input to the gate renders the semiconductor switch 210 selectivelyconductive or non-conductive, which in turn controls the power suppliedto the lighting load 208. The gate drive circuit 212 provides a controlinput to the semiconductor switch 210 in response to a control signalfrom a controller 214. The controller 214 may be any suitablecontroller, such as a microcontroller, a microprocessor, a programmablelogic device (PLD), or an application specific integrated circuit(ASIC).

A zero-crossing detect circuit 216 determines the zero-crossing pointsof the AC source voltage from the AC power supply 204. A zero-crossingis defined as the time at which the AC supply voltage transitions frompositive to negative polarity, or from negative to positive polarity, atthe beginning of each half-cycle. The zero-crossing information isprovided as an input to the controller 214. The controller 214 generatesthe gate control signals to operate the semiconductor switch 210 to thusprovide voltage from the AC power supply 204 to the lighting load 208 atpredetermined times relative to the zero-crossing points of the ACwaveform. A power supply 218 generates a direct-current (DC) voltageV_(CC), e.g., 5 volts, to power the controller 214 and other low voltagecircuitry of the dimmer 100.

The touch sensitive device 110 is coupled to the controller 214 througha stabilizing circuit 220 and a usage detection circuit 222. Thestabilizing circuit 220 is operable to stabilize the voltage output ofthe touch sensitive device 110. Accordingly, the voltage output of thestabilizing circuit 220 is not dependent on the magnitude of the forceof the point actuation on the touch sensitive device 110, but rather isdependent solely on the position of the point actuation. The usagedetection circuit 222 is operable to detect when a user is actuating thefront surface 108 of the dimmer 100. The controller 214 is operable tocontrol the operation of the stabilizing circuit 220 and the usagedetection circuit 222 and to receive control signals from both thestabilizing circuit and the usage detection circuit. Preferably, thestabilizing circuit 220 has a slow response time, while the usagedetection circuit 222 has a fast response time. Thus, the controller 214is operable to control the semiconductor switch 210 in response to thecontrol signal provided by the stabilizing circuit 220 when the usagedetection circuit 222 has detected an actuation of the touch sensitivedevice 110.

The controller 214 is operable to drive the plurality of statusindicators 114, e.g., light-emitting diodes (LEDs), which are locatedbehind the markers 112 on the front surface 108 of the dimmer 100. Thestatus indicators 114 also comprise the blue status indicator and theorange status indicator that are located immediately behind the icon116. The blue status indicator and the orange status indicator may beimplemented as separate blue and orange LEDs, respectively, or as asingle bi-colored LED.

The dimmer 100 further comprises an audible sound generator 224 coupledto the controller 214, such that the controller is operable to cause thesound generator to produce an audible sound in response to an actuationof the touch sensitive device 110. A memory 225 is coupled to thecontroller 214 and is operable to store control information of thedimmer 100.

FIG. 8 is a simplified schematic diagram of the circuitry for the touchsensitive device 110 and the controller 214, i.e., the stabilizingcircuit 220 and the usage detection circuit 222, according to a firstembodiment of the present invention. The resistive element 122 of thetouch sensitive device 110 is coupled between the DC voltage V_(CC) ofthe power supply 218 and circuit common, such that the DC voltage V_(CC)provides a biasing voltage to the touch sensitive device. The resistanceof the resistive element 122 may be, for example, 7.6 kΩ. The positionof contact between the conductive element 120 and the resistive element122 of the touch sensitive device 110 is determined by the position of apoint actuation on the front surface 108 of the bezel 106 of the dimmer100. The conductive element 120 is coupled to both the stabilizingcircuit 220 and the usage detection circuit 222. As shown in FIG. 7, thetouch sensitive device 110 of the dimmer 100 of the first embodiment isa three-wire device, i.e., the touch sensitive device has threeconnections or electrodes. The touch sensitive device provides oneoutput that is representative of the position of the point actuationalong a Y-axis, i.e., a longitudinal axis of the dimmer 100 as shown inFIG. 4B.

The stabilizing circuit 220 comprises a whacking-grade capacitor C230(that is, a capacitor having a large value of capacitance) and a firstswitch 232. The controller 214 is operable to control the first switch232 between a conductive state and a non-conductive state. When thefirst switch 232 is conductive, the capacitor C230 is coupled to theoutput of the touch sensitive device 110, such that the output voltageis filtered by the capacitor C230. When a touch is present, the voltageon the capacitor C230 will be forced to a steady-state voltagerepresenting the position of the touch on the front surface 108. When notouch is present, the voltage on the capacitor will remain at a voltagerepresenting the position of the last touch. The touch sensitive device110 and the capacitor C230 form a sample-and-hold circuit. The responsetime of the sample-and-hold circuit is determined by a resistance R_(D)of the touch sensitive device (i.e., the resistance R_(E) of theresistive element and a contact resistance R_(C)) and the capacitance ofthe capacitor C230. During typical actuation, the contact resistanceR_(C) is small compared to the value of R_(E), such that a firstcharging time constant T₁, is approximately equal to R_(E) ·C₂₃₀. Thistime constant T₁ is preferably 13 ms, but may be anywhere between 6 msand 15 ms.

When a light or transient press is applied to the touch sensitive device110, the capacitor C230 will continue to hold the output at the voltagerepresenting the position of the last touch. During the release of thetouch sensitive device 110, transient events may occur that produceoutput voltages that represent positions other than the actual touchposition. Transient presses that are shorter than the first chargingtime constant T₁ will not substantially affect the voltage on thecapacitor C230, and therefore will not substantially affect the sensingof the position of the last actuation. During a light press, a secondcharging time constant T₂ will be substantially longer than duringnormal presses, i.e., substantially larger than the first time constantT₁, due to the higher contact resistance R_(C). However, thesteady-state value of the voltage across the capacitor C230 will be thesame as for a normal press at the same position. Therefore, the outputof the stabilizing circuit 220 is representative of only the position ofthe point of actuation of the touch sensitive device 110.

The usage detection circuit 222 comprises a resistor R234, a capacitorC236, and a second switch 238, which is controlled by the controller214. When the switch 238 is conductive, the parallel combination of theresistor R234 and the capacitor C236 is coupled to the output of thetouch sensitive device 110. Preferably, the capacitor C236 has asubstantially small capacitance C₂₃₆, such that the capacitor C236charges substantially quickly in response to all point actuations on thefront surface 108. The resistor R234 allows the capacitor C236 todischarge quickly when the switch 238 is non-conductive. Therefore, theoutput of the usage detection circuit 222 is representative of theinstantaneous usage of the touch sensitive device 110.

The controller 214 controls the switches 232, 238 in a complementarymanner. When the first switch 232 is conductive, the second switch 238is non-conductive, and vice versa. The controller 214 controls thesecond switch 238 to be conductive for a short period of time t_(USAGE)once every half cycle of the voltage source 204 to determine whether theuser is actuating the front surface 108. Preferably, the short period oftime t_(USAGE) is approximately 100 μsec or 1% of the half-cycle(assuming each half-cycle is 8.33 msec long). For the remainder of thetime, the first switch 232 is conductive, such that the capacitor C230is operable to charge accordingly. When the first switch 232 isnon-conductive and the second switch 238 is conductive, thewhacking-grade capacitor C230 of the stabilizing circuit 220 is unableto discharge at a significant rate, and thus the voltage developedacross the capacitor C230 will not change significantly when thecontroller 214 is determining whether the touch sensitive device 110 isbeing actuated through the usage detection circuit 222.

FIG. 9 is a simplified schematic diagram of the audible sound generator224 of the dimmer 100. The audible sound generator 224 uses an audiopower amplifier integrated circuit (IC) 240, for example, part numberTPA721 manufactured by Texas Instruments, Inc., to generate a sound froma piezoelectric or magnetic speaker 242. The amplifier IC 240 is coupledto the DC voltage V_(CC) (pin 6) and circuit common (pin 7) to power theamplifier IC. A capacitor C244 (preferably having a capacitance of 0.1μF) is coupled between the DC voltage V_(CC) and circuit common todecouple the power supply voltage and to ensure the output totalharmonic distortion (THD) is as low as possible.

The audible sound generator 224 receives a SOUND ENABLE signal 246 fromthe controller 214. The SOUND ENABLE signal 246 is provided to an enablepin (i.e., pin 1) on the amplifier IC 240, such that the audible soundgenerator 224 will be operable to generate the sound when the SOUNDENABLE signal is at a logic high level.

The audible sound generate 224 further receives a SOUND WAVE signal 248from the controller 214. The SOUND WAVE signal 248 is an audio signalthat is amplified by the amplifier IC 240 to generate the appropriatesound at the speaker 242. The SOUND WAVE signal 248 is first filtered bya low-pass filter comprising a resistor R250 and a capacitor C252.Preferably, the resistor R250 has a resistance of 1 kΩ and the capacitorC252 has a capacitance of 0.1 nF. The filtered signal is then passedthrough a capacitor C254 to produce an input signal V_(IN). Thecapacitor C254 allows the amplifier IC to bias the input signal V_(IN)to the proper DC level for optimum operation and preferably has acapacitance of 0.1 μF. The input signal V_(IN) is provided to a negativeinput (pin 4) of the amplifier IC 240 through a input resistor R_(I) Apositive input (pin 3) of the amplifier IC 240 and with a bypass pin(pin 2) are coupled to circuit common through a bypass capacitor C256(preferably, having a capacitance of 0.1 μF).

The output signal V_(OUT) of the amplifier IC 240 is produced from apositive output (pin 5) to a negative output (pin 8) and is provided tothe speaker 242. The negative input (pin 4) is coupled to the positiveoutput (pin 5) through an output resistor R_(F). The gain of theamplifier IC 240 is set by the input resistor R_(I) and the feedbackresistor R_(F), i.e.,

Gain=V _(OUT) /V _(IN)=−2·(R _(F) /R _(I)).

Preferably, the input resistor R_(I) and the output resistor R_(F) bothhave resistances of 10 kΩ, such that the gain of the amplifier IC 240 isnegative two (−2).

FIG. 10 is a flowchart of a touch dimmer procedure 300 executed by thecontroller 214 of the dimmer 100 according to the present invention.Preferably, the touch dimmer procedure 300 is called from the main loopof the software of the controller 214 once every half cycle of the ACvoltage source 204. The touch dimmer procedure 300 selectively executesone of three procedures depending upon the state of the dimmer 100. Ifthe dimmer 100 is in an “Idle” state (i.e., the user is not actuatingthe touch sensitive device 110) at step 310, the controller 214 executesan Idle procedure 400. If the dimmer 100 is in an “ActiveHold” state(i.e., the user is presently actuating the touch sensitive device 110)at step 320, the controller 214 executes an ActiveHold procedure 500. Ifthe dimmer 100 is in a “Release” state (i.e., the user has recentlyceased actuating the touch sensitive device 110) at step 330, thecontroller 214 executes a Release procedure 600.

FIG. 11 is a flowchart of the Idle procedure 400 according to thepresent invention. The controller 114 uses a “sound flag” and a “soundcounter” to determine when to cause the audible sound generator 224 togenerate the audible sound. The purpose of the sound flag is to causethe sound to be generated the first time that the controller 214executes the ActiveHold procedure 500 after being in the Idle state. Ifthe sound flag is set, the controller 214 will cause the sound to begenerated. The sound counter is used to ensure that the controller 214does not cause the audible sound generator 224 to generate the audiblesound too often. The sound counter preferably has a maximum soundcounter value S_(MAX), e.g., approximately 425 msec. Accordingly, thereis a gap of approximately 425 msec between generations of the audiblesound. The sound counter is started during the Release procedure 600 aswill be described in greater detail below. Referring to FIG. 11, uponentering the Idle state, the controller 214 sets the sound flag at step404 if the sound flag is not set at step 402.

An “LED counter” and an “LED mode” are used by the controller 214 tocontrol the status indicators 114 (i.e., the LEDs) of the dimmer 100.The controller 214 uses the LED counter to determine when apredetermined time t_(LED) has expired since the touch sensitive device110 was actuated. When the predetermined time t_(LED) has expired, thecontroller 214 will change the LED mode from “active” to “inactive”.When the LED mode is “active”, the status indicators 114 are controlledsuch that one or more of the status indicators are illuminated to abright level. When the predetermined time t_(LED) expires, the LED modeis changed to “inactive”, i.e., the status indicators 114 are controlledsuch that one or more of the status indicators are illuminated to a dimlevel. Referring to FIG. 11, if the LED counter is less than a maximumLED counter value L_(MAX) at step 410, the LED counter is incremented atstep 412 and the process moves on to step 418. However, if the LEDcounter is not less than the maximum LED counter value L_(MAX), the LEDcounter is cleared at step 414 and the LED mode is set to inactive atstep 416. Since the touch dimmer procedure 300 is executed once everyhalf cycle, the predetermined time t_(LED) is preferably equal to

t _(LED) =T _(HALF) L _(MAX),

where T_(HALF) is the period of a half cycle.

Next, the controller 214 reads the output of the usage detection circuit222 to determine if the touch sensitive device 110 is being actuated.Preferably, the usage detection circuit 222 is monitored once every halfcycle of the voltage source 204. At step 418, the controller 214 opensswitch 232 and closes switch 238 to couple the resistor R234 and thecapacitor C236 to the output of the touch sensitive device 110. Thecontroller 214 determines the DC voltage of the output of the usagedetection circuit 222 at step 420, preferably, by using ananalog-to-digital converter (ADC). Next, the controller 214 closesswitch 232 and opens switch 238 at step 422.

At step 424, if there is activity on the front surface 108 of the dimmer100, i.e., if the DC voltage determined at step 420 is above apredetermined minimum voltage threshold, then an “activity counter” isincremented at step 426. Otherwise, the activity counter is cleared atstep 428. The activity counter is used by the controller 214 todetermine if the DC voltage determined at step 420 is the result of apoint actuation of the touch sensitive device 110 rather than noise orsome other undesired impulse. The use of the activity counter is similarto a software “debouncing” procedure for a mechanical switch, which iswell known in the art. If the activity counter is not less than amaximum activity counter value AMAX at step 430, then the dimmer stateis set to the ActiveHold state at step 432. Otherwise, the processsimply exits at step 434.

FIGS. 12A and 12B are flowcharts of the ActiveHold procedure 500, whichis executed once every half cycle when the touch sensitive device 110 isbeing actuated, i.e., when the dimmer 100 is in the ActiveHold state.First, a determination is made as to whether the user has stopped using,i.e., released, the touch sensitive device 110. The controller 214 opensswitch 232 and closes switch 238 at step 510, and reads the output ofthe usage detection circuit 222 at step 512. At step 514, the controller214 closes switch 232 and opens switch 238. If there is no activity onthe front surface 108 of the dimmer 100 at step 516, the controller 214increments an “inactivity counter” at step 518. The controller 214 usesthe inactivity counter to make sure that the user is not actuating thetouch sensitive device 110 before entering the Release mode. If theinactivity counter is less than a maximum inactivity counter valueI_(MAX) at step 520, the process exits at step 538. Otherwise, thedimmer state is set to the Release state at step 522, and then theprocess exits.

If there is activity on the touch sensitive device 110 at step 516, thecontroller 214 reads the output of the stabilizing circuit 220, which isrepresentative of the position of the point actuation on the frontsurface 108 of the dimmer 100. Since the switch 232 is conductive andthe switch 238 is non-conductive, the controller 214 determines the DCvoltage at the output of the stabilizing circuit 220, preferably usingan ADC, at step 524.

Next, the controller 214 uses a buffer to “filter” the output ofstabilizing circuit 220. When a user actuates the touch sensitive device110, the capacitor C230 will charge to approximately the steady-statevoltage representing the position of the actuation on the front surface108 across a period of time determined by the first time constant T₁ aspreviously described. Since the voltage across the capacitor C230, i.e.,the output of the stabilizing circuit 220, is increasing during thistime, the controller 214 delays for a predetermined period of time atstep 525, preferably, for approximately three (3) half cycles.

When a user's finger is removed from the front surface 108 of the bezel106, subtle changes in the force and position of the point actuationoccur, i.e., a “finger roll-off” event occurs. Accordingly, the outputsignal of the touch sensitive device 110 is no longer representative ofthe position of the point actuation. To prevent the controller 214 fromprocessing reads during a finger roll-off event, the controller 214saves the reads in the buffer and processes the reads with a delay,e.g., six half cycles later. Specifically, when the delay is over atstep 525, the controller 214 rotates the new read (i.e., from step 524)into the buffer at step 526. If the buffer has at least six reads atstep 528, the controller 214 averages the reads in the fifth and sixthpositions in the buffer at step 530 to produce the touch position data.In this way, when the user stops actuating the touch sensitive device110, the controller 214 detects this change at step 516 and sets thedimmer state to the Release state at step 522 before the controllerprocesses the reads saved in the buffer near the transition time of thetouch sensitive device.

At step 532, the controller 114 determines if the touch position datafrom step 530 is in the keepout region 118 (as shown in FIG. 4B). If thetouch position data is in the keepout region 118, the ActiveHoldprocedure 500 simply exits at step 538. Otherwise, a determination ismade at step 534 as to whether the sound should be generated.Specifically, if the sound flag is set and if the sound counter hasreached a maximum sound counter value S_(MAX), the controller 214 drivesthe SOUND ENABLE signal 246 high and provides the SOUND WAVE signal 248to the audible sound generator 224 to generate the sound at step 535.Further, the sound flag is cleared at step 536 such that the sound willnot be generated as long as the dimmer 100 remains in the ActiveHoldstate.

If the touch position data is in the toggle area, i.e., the lowerportion of the front surface 108 of the bezel 106 surrounding the icon116 (as shown in FIG. 4A), at step 540, the controller 214 processes theactuation of the touch sensitive device 110 as a toggle. If the lightingload 208 is presently off at step 542, the controller 214 turns thelighting load on. Specifically, the controller 214 illuminates the icon116 with the blue status indicator at step 544 and dims the lightingload 208 up to the preset level, i.e., the desired lighting intensity ofthe lighting load, at step 546. If the lighting load is presently on atstep 542, the controller 214 turns on the orange status indicator behindthe icon 116 at step 548 and fades the lighting load 208 to off at step550.

If the touch position data is not in the toggle area at step 540, thecontroller 214 scales the touch position data at step 552. The output ofthe stabilizing circuit 220 is a DC voltage between a maximum value,i.e., substantially the DC voltage V_(CC), and a minimum value, whichcorresponds to the DC voltage providing by the touch sensitive device110 when a user is actuating the lower end of the upper portion of thefront surface 108 of the bezel 106. The controller 214 scales this DCvoltage to be a value between off (i.e., 1%) and full intensity (i.e.,100%) of the lighting load 208. At step 554, the controller 214 dims thelighting load 208 to the scaled level produced in step 552.

Next, the controller 214 changes the status indicators 114 locatedbehind the markers 112 on the front surface 108 of the bezel 106. As auser actuates the touch sensitive device 110 to change intensity of thelighting load 208, the controller 214 decides whether to change thestatus indicator 114 that is presently illuminated. Since there areseven (7) status indicators to indicate an intensity between 1% and100%, the controller 214 may illuminate the first status indicator,i.e., the lowest status indicator, to represent an intensity between 1%and 14%, the second status indicator to represent an intensity between15% and 28%, and so on. The seventh status indicator, i.e., the higheststatus indicator, may be illuminated to represent an intensity between85% and 100%. Preferably, the controller 214 uses hysteresis to controlthe status indicators 114 such that if the user actuates the frontsurface 108 at a boundary between two of the regions of intensitiesdescribed above, consecutive status indicators do not toggle back andforth.

Referring to FIG. 12B, a determination is made as to whether a change isneeded as to which status indicator is illuminated at step 556. If thepresent LED (in result to the touch position data from step 530) is thesame as the previous LED, then no change in the LED is required. Thepresent LED is set the same as the previous LED at step 558, ahysteresis counter is cleared at step 560, and the process exits at step570.

If the present LED is not the same as the previous LED at step 556, thecontroller 214 determines if the LED should be changed. Specifically, atstep 562, the controller 214 determines if present LED would change ifthe light level changed by 2% from the light level indicated by thetouch position data. If not, the hysteresis counter is cleared at step560 and the process exits at step 570. Otherwise, the hysteresis counteris incremented at step 564. If the hysteresis counter is less than amaximum hysteresis counter value H_(MAX) at step 566, the process exitsat step 570. Otherwise, the LEDs are changed accordingly based on thetouch position data at step 568.

FIG. 13 is a flowchart of the Release procedure 600, which is executedafter the controller 214 sets the dimmer state to the Release state atstep 522 of the ActiveHold procedure 500. First, a save flag is set atstep 610. Next, the sound counter is reset at step 612 to ensure thatthe sound will not be generated again, e.g., for preferably 18 halfcycles. At step 618, a determination is made as to whether the dimmer100 is presently executed a fade-to-off. If not, the present level issaved as the preset level in the memory 225 at step 620. Otherwise, thedesired lighting intensity is set to off at step 622, the long fadecountdown in started at step 624, and the preset level is saved as offin the memory 225.

Alternatively, the controller 214 could cause the audible soundgenerator 224 to generate different sounds in response to differentpresses of the touch sensitive device. For example, the audible soundgenerator could produce a first sound in response to a toggle event,i.e., an actuation of the lower portion of the front surface 108 of thebezel 106 surrounding the icon 116, and a second sound in response to achange intensity event, i.e., an actuation of the upper portion of thefront surface 108 of the bezel 106.

FIGS. 14A and 14B are flowcharts of an ActiveHold procedure 650 forgenerating a first sound and a second sound in response to a toggleevent and a change intensity event, respectively. Referring to FIG. 14B,if the actuation of the touch sensitive member 110 is in the toggle areaat step 540, the controller 214 determines at step 652 if the soundshould be generated. Specifically, if the sound flag is set and if thesound counter has reached a maximum sound counter value S_(MAX), thecontroller 214 drives the SOUND ENABLE signal 246 high and provides afirst sound wave to the audible sound generator 224 to generate a firstsound at step 654. Further, the sound flag is cleared at step 656 andthe process continues on to toggle the lighting load 208. If theactuation is not a toggle event at step 540 and if the sound should begenerated at step 658, the controller 214 drives the SOUND ENABLE signal246 high and provides a second sound wave to the audible sound generator224 to generate a second sound at step 660. At step 662, the sound flagis cleared ant the process continues on to adjust the intensity of thelighting load 208.

Further, the controller 214 may be operable to cause the audible soundgenerator 224 to generate the audible sound in response to both a pressand a release of the touch sensitive device 110 to mimic the sound thatis created when a tactile switch, e.g., the switch controlled by thecontrol switch actuator 18 of the prior art dimmer switch 10, ispressed. FIG. 14C is a flowchart of a Release procedure 680, whichincludes an additional step 682 for causing the audible sound generatorto create a release sound. Preferably, the release sound is a differentsound than was created at step 535 of the ActiveHold procedure 500.

FIG. 15A and FIG. 15B are simplified schematic diagrams of the circuitryfor a four-wire touch sensitive device 710 and a controller 714according to a second embodiment of the present invention. The four-wiretouch sensitive device 710 has four connections, i.e., electrodes, andprovides two outputs: a first output representative of the position of apoint actuation along the Y-axis, i.e., the longitudinal axis of thedimmer 100 a shown in FIG. 4B, and a second output representative of theposition of the point actuation along the X-axis, i.e., an axisperpendicular to the longitudinal axis. The four-wire touch sensitivedevice 710 provides the outputs depending on how the DC voltage V_(CC)is connected to the touch sensitive device. A stabilizing circuit 720 isoperatively coupled to the first output and a usage detection circuit722 is operatively coupled to the second output.

The controller 714 controls three switches 760, 762, 764 to connect thetouch sensitive device 710 to the DC voltage V_(CC) accordingly. Whenthe switches 760, 762, 764 are connected in position A as shown in FIG.15A, the DC voltage V_(CC) is coupled across the Y-axis resistor, andthe X-axis resistor provides the output to the stabilizing circuit 720.When the switches 760, 762, 764 are connected in position B as shown inFIG. 15B, the DC voltage V_(CC) is coupled across the X-axis resistor,and the Y-axis resistor provides the output to the usage detectioncircuit 722. Since the controller 714 provides one output signal tocontrol whether the stabilizing circuit 720 or the usage detectioncircuit 722 is coupled to the touch sensitive device 110, the softwareexecuted by the controller 714 is the same as the software executed bythe controller 214 shown in FIGS. 10-13.

FIG. 15C is a simplified schematic diagram of the circuitry for thefour-wire touch sensitive device 710 and a controller 814 according to athird embodiment of the present invention. The controller 814 isoperable to read the position of a point actuation on the four-wiretouch sensitive device 710 along both the Y-axis and the X-axis. Whendetermining the position along the Y-axis, the controller 814 operatesthe same as the controller 714 shown in FIGS. 15A and 15B by controllingthe switches 760, 762, 764 as described above.

An additional stabilizing circuit 870 is provided for determining theposition of the point actuation along the X-axis. The additionalstabilizing circuit 870 comprises a whacking-grade capacitor C872. Thecontroller 814 controls a switch 874 to selectively switch the output ofthe X-axis between the usage detection circuit 722 and the additionalstabilizing circuit 870. The controller 814 controls the switch 874 in asimilar fashion to how the controller 214 controls the switches 232, 238(as shown in FIG. 8).

FIGS. 16A and 16B are a perspective view and a front view, respectively,of a touch dimmer 900 according to a fourth embodiment of the presentinvention. FIG. 17A is a bottom cross-sectional view and FIG. 17B is anenlarged partial bottom cross-sectional view of the dimmer 900. FIG. 18Ais a left side cross-sectional view and FIG. 18B is an enlarged partialleft side cross-sectional view of the dimmer 900.

The touch dimmer 900 includes a thin touch sensitive actuator 910comprising an actuation member 912 extending through a bezel 914. Thedimmer 900 further comprises a faceplate 916, which has a non-standardopening 918 and mounts to an adapter 920. The bezel 914 is housed behindthe faceplate 916 and extends through the opening 918. The adapter 920connects to a yoke 922, which is adapted to mount the dimmer 900 to astandard electrical wallbox. A main printed circuit board (PCB) 924 ismounted inside an enclosure 926 and includes the some of the electricalcircuitry of the dimmer 200, e.g., the semiconductor switch 210, thegate drive circuit 212, the controller 214, the zero-crossing detectcircuit 216, the power supply 218, the stabilizing circuit 220, theusage detection circuit 222, the audible sound generator 224, and thememory 225, of the dimmer 200. The thin touch sensitive actuator 910preferably extends beyond the faceplate by 1/16″, i.e., has a height of1/16″, but may have a height in the range of 1/32″ to 3/32″. Preferably,the touch sensitive actuator 910 has a length of 3⅝″ and a width of3/16″. However, the length and the width of the touch sensitive actuator910 may be in the ranges of 2⅝″-4″ and ⅛″-¼″, respectively.

The touch sensitive actuator 910 operates to contact a touch sensitivedevice 930 inside the touch dimmer 900. The touch sensitive device 930is contained by a base 932. The actuation member 912 includes aplurality of long posts 934, which contact the front surface of thetouch sensitive device 930 and are arranged in a linear array along thelength of the actuation member. The posts 934 act as force concentratorsto concentrate the force from an actuation of the actuation member 912to the touch sensitive device 930.

A plurality of status indicators 936 are arranged in a linear arraybehind the actuation member 912. The status indicators are mounted on adisplay PCB 938, i.e., a status indicator support board, which ismounted between the touch sensitive device 930 and the bezel 914. FIG.19 is a perspective view of the display PCB 938. The display PCB 938includes a plurality of holes 939, which the long posts 934 extendthrough to contact the touch sensitive device 930. The actuation member912 is preferably constructed from a translucent material such that thelight of the status indicators 936 is transmitted to the surface of theactuation member. A plurality of short posts 940 are provided in theactuation member 912 directly above the status indicators 936 to operateas light pipes for the linear array of status indicators. The displayPCB 938 comprises a tab 952 having a connector 954 on the bottom sidefor connecting the display PCB 938 to the main PCB 924.

The actuation member 912 comprises a notch 942, which separates a lowerportion 944 and an upper portion 946 of the actuation member. Uponactuation of the lower portion 944 of the actuation member 912, thedimmer 900 causes the connected lighting load to toggle from on to off(and vice versa). Preferably, a blue status indicator 948 and an orangestatus indicator 950 are located behind the lower portion 944, such thatthe lower portion is illuminated with blue light when the lighting loadis on and illuminated with orange light with the lighting load is off.Actuation of the upper portion 946 of the actuation member 912, i.e.,above the notch 942, causes the intensity of the lighting load to changeto a level responsive to the position of the actuation on the actuationmember 912. The status indicators 936 behind the status markers 112 areilluminated to display the intensity of the lighting load as with thepreviously-discussed touch dimmer 100.

FIG. 20 is an enlarged partial bottom cross-sectional view of a thintouch sensitive actuator 960 according to a fifth embodiment of thepresent invention. The touch sensitive actuator 960 comprises anactuation member 962 having two posts 964 for actuating the touchsensitive device 930. A plurality of status indicators 966 are mountedon a flexible display PCB 968, i.e., a flexible status indicator supportboard, which the posts 964 of the actuation member 962 are operable toactuate the touch sensitive device 930 through. The status indicators966 are preferably blue LEDs and are arranged along the length of theactuation member 962. Preferably, the actuation member 962 isconstructed from a translucent material such that the light of thestatus indicators 966 is transmitted to the surface of the actuationmember.

FIG. 21A is a perspective view and FIG. 21B is an enlarged side view ofa touch dimmer 1000 according to a sixth embodiment of the presentinvention. The dimmer 1000 comprises a bezel 1010 having a front surface1012 and a faceplate 1014 having an opening 1016. Actuation of the frontsurface 1012 actuates a touch sensitive device (not shown) inside thedimmer (in a similar fashion as the dimmer 100). The dimmer 1000 furthercomprises a shallow domed protrusion 1018, i.e., a raised area, on thefront surface 1012 of the bezel 1010. Actuation of the shallow domedprotrusion 1018 causes the dimmer 1000 to toggle a connected lightingload (not shown) from off to on (and vice versa). Actuation of an upperportion 1020 of the front surface 1012 of the bezel 1010 above the domeprotrusion 1018 causes the dimmer 1000 to change the intensity of thelighting load. The dimmer 1000 further comprises a status indicator,e.g., an LED, immediately behind the shallow domed protrusion 1018 toilluminate the protrusion.

Preferably, a keepout region 1022 is provided between the domeprotrusion 1018 and the upper portion 1020 of the front surface 1012 ofthe bezel 1010. The dimmer 1000 does not respond to actuations of thekeepout region 1022. Accordingly, a portion of the touch sensitivedevice immediately below the domed protrusion 1018, i.e., the “toggleactuator”, and the upper portion 1020 is disabled to provide the keepoutregion 1022.

FIG. 22 is a front view of a touch dimmer 1100 according to a seventhembodiment of the present invention. The dimmer 1100 comprises a touchsensitive device 1110 and a faceplate 1112 having a designer-styleopening 1114. The touch sensitive device 1110 is surrounded by a bezel1116, i.e., a thin escutcheon frame, such that the touch sensitivedevice 1110 is provided in a rectangular opening 1118 of the bezel. Aplurality of status indicators 1120 are arranged in a linear array onone side of the bezel 1116.

The touch sensitive device 1110 has a marker dot 1122 and a separatorline 1124 printed on its front surface. The separator line 1124 islocated between a lower portion 1126 and an upper portion 1128 of thetouch sensitive device 1110. Actuation of the lower portion 1126surrounding the marker dot 1122 will toggle a connected lighting load onand off. Actuation of the upper portion 1128 of the touch sensitivedevice

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

1. A load control device for controlling the amount of power deliveredto an electrical load from an AC power source, the load control devicecomprising: a semiconductor switch operable to be coupled in serieselectrical connection between the source and the load, the semiconductorswitch having a control input for controlling the semiconductor switchbetween a non-conductive state and a conductive state; a controlleroperatively coupled to the control input of the semiconductor switch forcontrolling the semiconductor switch between the non-conductive stateand the conductive state; a touch screen actuator having a touchsensitive front surface responsive to a plurality of point actuations,each characterized by a position and a force, the touch screen actuatorhaving an output operatively coupled to the controller for providing acontrol signal representative of the position of the point actuation; avisual display responsive to the controller; and an audible soundgenerator responsive to the controller; wherein the controller isoperable to cause the visual display to illuminate and the audible soundgenerator to generate an audible sound in response to the control signalof the touch screen actuator.
 2. A user interface for a lightingcontrol, the user interface comprising: a touch screen actuator having atouch sensitive front surface responsive to a plurality of pointactuations, each characterized by a position and a force, the touchscreen actuator having an output for providing a control signalrepresentative of the position of the point actuation; a visual displayoperable to illuminate in response to the control signal of the touchscreen actuator; and an audible sound generator operable to generate anaudible sound in response to the control signal of the touch screenactuator.
 3. A load control device for controlling the amount of powerdelivered to an electrical load from an AC power source, the loadcontrol device comprising: a semiconductor switch operable to be coupledin series electrical connection between the source and the load, thesemiconductor switch having a control input for controlling thesemiconductor switch between a non-conductive state and a conductivestate; a controller operatively coupled to the control input of thesemiconductor switch for controlling the semiconductor switch betweenthe non-conductive state and the conductive state; a touch screenactuator having a touch sensitive front surface responsive to aplurality of point actuations, each characterized by a position and aforce, the touch screen actuator having an output operatively coupled tothe controller for providing a first control signal in response to afirst point actuation and a second control signal in response to asecond point actuation; and an audible sound generator responsive to thecontroller; wherein the controller is operable to cause the audiblesound generator to generate a first audible sound in response to thefirst control signal and a second audible sound in response to thesecond control signal.
 4. A user interface for a lighting control, theuser interface comprising: a touch screen actuator having a touchsensitive front surface responsive to a plurality of point actuations,each characterized by a position and a force, the touch screen actuatorhaving an output for providing a first control signal in response to afirst point actuation and a second control signal in response to asecond point actuation; and an audible sound generator operable togenerate a first audible sound in response to the first control signaland a second audible sound in response to the second control signal. 5.A load control device for controlling the amount of power delivered toan electrical load from an AC power source, the load control devicecomprising: a semiconductor switch operable to be coupled in serieselectrical connection between the source and the load, the semiconductorswitch having a control input for controlling the semiconductor switchbetween a non-conductive state and a conductive state; a controlleroperatively coupled to the control input of the semiconductor switch forcontrolling the semiconductor switch between the non-conductive stateand the conductive state; a touch screen actuator having a touchsensitive front surface responsive to a plurality of point actuations,each characterized by a position and a force, the touch screen actuatoroperable to begin providing a control signal to the controller when themagnitude of the force of each of the point actuations exceedssubstantially a minimum magnitude and to cease providing the controlsignal when the magnitude of the force subsequently decreases belowsubstantially the minimum magnitude of the point actuation; and anaudible sound generator responsive to the controller; wherein thecontroller is operable to cause the audible sound generator to generatea first audible sound in response to the control signal when themagnitude of the force of each of the point actuations exceedssubstantially the minimum magnitude, and to generate a second audiblesound in response to the control signal when the magnitude of the forcesubsequently decreases below substantially the minimum magnitude of thepoint actuation.
 6. A user interface for a lighting control, the userinterface comprising: a touch screen actuator having a touch sensitivefront surface responsive to a plurality of point actuations, eachcharacterized by a position and a force, the touch screen actuatoroperable to begin providing a control signal when the magnitude of theforce of each of the point actuations exceeds substantially a minimummagnitude and to cease providing the control signal when the magnitudeof the force subsequently decreases below substantially the minimummagnitude of the point actuation; and an audible sound generatoroperable to generate a first audible sound in response to the controlsignal when the magnitude of the force of each of the point actuationsexceeds substantially the minimum magnitude, and to generate a secondaudible sound in response to the control signal when the magnitude ofthe force subsequently decreases below substantially the minimummagnitude of the point actuation.
 7. A control structure for anelectrical control system for producing a variable output electricalsignal to an electrical load for controllably varying the output of saidload, said control structure comprising: (a) an enclosed volume whichcontains control electronics; (b) a cover plate on one surface of saidenclosed volume having a planar front surface and having a rectangularopening therein; (c) a transparent touch pad disposed in saidrectangular opening and coupled to said control electronics and adaptedto produce an output signal which is related to the position within thearea of said touch pad at which said touch pad is touched by anoperator; (d) a plurality of vertically arranged markers printed on saidtouch pad to serve as scale indicator; (e) a plurality of statusindicators coupled to said control electronics for illuminatingrespective discrete locations on said touch pad which lie on a linealong the length of said touch pad and in a predetermined alignment withrespective ones of said printed markers and being respectivelyilluminated adjacent the position on said touch pad at which said touchpad is touched by an operator; (f) a small marker at the bottom of saidtouch pad and in the center of the width of said touch pad, wherein saidcontrol electronics are operable to toggle said load when said touch padis touched at the location of said small marker; and (g) at least afirst status indicator connected to said control electronics andpositioned to illuminate said marker and when said touch pad is touchedat said small diameter marker dot to turn off said load.
 8. The controlstructure of claim 7, wherein said load is at least one dimmable lightsource.
 9. The control structure of claim 7, wherein said controlstructure is a wall box structure adapted for mounting on a wall. 10.The control structure of claim 7, wherein said touch pad issubstantially coplanar with said planar front surface.
 11. The controlstructure of claim 7, wherein said touch pad is disposed in a planeparallel to and above the plane of said planar front surface.
 12. Thecontrol structure of claim 7, wherein said rectangular opening has aheight of about 4 to about 6 times its width.
 13. The control structureof claim 7, wherein said rectangular openings has a height of about 5times its width.
 14. The control structure of claim 7, wherein saidrectangular opening is a designer-style opening having a height which isabout twice its width.
 15. The control structure of claim 7, whereinsaid rectangular opening fills substantially the full area of said coverplate and is surrounded by a thin outer rim of said cover plate.
 16. Thecontrol structure of claim 7, wherein said plurality of LEDs consist ofat least 7 blue LEDs.
 17. The control structure of claim 7, wherein saiddiscrete locations illuminated by said plurality of LEDs are disposedalong one vertical edge of said touch pad.
 18. The control structure ofclaim 7, wherein the plurality of status indicators comprise a pluralityof LEDs.
 19. The control structure of claim 18, wherein said discretelocations are vertically disposed along the center of the width of saidtouch pad, and wherein said LEDs are blue LEDs.
 20. The controlstructure of claim 7, further comprising: a second status indicator ofcolor different from that of said first status indicator, the secondstatus indicator coupled to said control electronics and operable toilluminate said small marker when said touch screen is touched at anylocation.
 21. The control structure of claim 18, wherein said LEDsextend through said touch screen at said discrete locations.
 22. Thecontrol structure of claim 18, wherein said LEDs are disposed beneathand are spaced from the bottom of said touch screen and furtherincluding light conductors extending from each of said LEDs torespective ones of said discrete locations behind said touch screen. 23.The control structure of claim 7, further comprising: an airgap switchin said enclosed volume; and an operator for the airgap switch, saidoperator including a lever having an end which extends only sufficientlythrough said cover plate at the bottom of said rectangular opening to begripped by the fingernail of an operator.
 24. The control structure ofclaim 7, further comprising: a rectangular frame for supporting saidtouch pad at its outer periphery, said frame extending through saidrectangular opening, said frame comprising a shallow cup having a flangeat its open end, said flange being captured by a cooperating extensionfrom the exterior of said rectangular opening, said touch pad widthbeing greater than the width of said rectangular opening.
 25. Thecontrol structure of claim 7, wherein said small marker comprises asmall marker dot.
 26. A control structure for an electrical controlsystem for producing a variable output electrical signal to anelectrical load for controllably varying the output of said load, saidcontrol structure comprising: (a) an enclosed volume which containscontrol electronics; (b) cover plate on one surface of said enclosedvolume having a planar front surface and having a rectangular openingtherein; (c) a transparent touch pad disposed in said rectangularopening and coupled to said control electronics and adapted to producean output signal which is related to the position within the area ofsaid touch pad at which said touch pad is touched by an operator; (d) athin escutcheon frame surrounding said rectangular opening; (e) aplurality of status indicators coupled to said control electronics anddisposed along the length of one side of said escutcheon frame andadjacent said touch pad; (f) a small marker at the bottom of said touchpad and in the center of the width of said touch pad, wherein thecontrol electronics are operable to turn off said load when said touchpad is touched at the location of said small marker; and (g) at least afirst LED positioned to illuminate said small marker and connected tosaid control electronics when said touch pad is touched at said smallmarker to turn off said load.
 27. The control structure of claim 26,wherein said load is at least one dimmable light source.
 28. The controlstructure of claim 26, wherein said control structure is a wall boxstructure adapted for mounting on a wall.
 29. The control structure ofclaim 26, wherein said touch pad is substantially coplanar with saidplanar front surface.
 30. The control structure of claim 26, whereinsaid touch pad is disposed in a plane parallel to and beneath the planeof said planar front surface.
 31. The control structure of claim 26,wherein said rectangular opening has a height of about 4 to about 6times its width.
 32. The control structure of claim 26, wherein theplurality of status indicators comprise a plurality of LEDs.
 33. Thestructure of claim 32, wherein said plurality of LEDs consist of atleast 7 blue LEDs.
 34. The control structure of claim 26, wherein saidsmall marker comprises a small marker dot.
 35. The control structure ofclaim 26, further comprising: an airgap switch in said enclosed volume;and an operator for said airgap switch, said operator comprising a leverhaving an end which extends only sufficiently through said cover plateat the bottom of said rectangular opening to be gripped by the fingernail of an operator.
 36. A control structure for an electrical controlsystem for producing a variable output electrical signal to anelectrical load for controllably varying an output of said load, saidcontrol structure comprising: (a) an enclosed volume which containscontrol electronics; (b) a cover plate on one surface of said enclosedvolume having a planar front surface and having a rectangular openingtherein; (c) a touch pad disposed in said rectangular opening andcoupled to said control electronics and adapted to produce an outputsignal which is related to the position within the area of said touchpad at which said touch pad is touched by an operator; and (d) amanually sensible area at the bottom of said touch pad, whereindepression of said area operates an on/off operation of said controlelectronics.
 37. The control structure of claim 36, wherein saidmanually sensible area is a shallow-raised area.
 38. The controlstructure of claim 36, wherein said manually sensible area is a shallowdomed protrusion.
 39. The control structure of claim 36, wherein saidrectangular opening has a height of about 4 to about 6 times its height.40. The control structure of claim 36, further comprising: a firststatus indicator positioned to illuminate said manually sensible area.41. The control structure of claim 40, wherein said manually sensiblearea is a shallow-raised area.
 42. The control structure of claim 40,wherein said manually sensible area is a shallow domed protrusion. 43.The control structure of claim 36, wherein said load is at least onedimmable light source.
 44. The control structure of claim 36, whereinsaid control structure is a wall box structure adapted for mounting on awall.
 45. The control structure of claim 36, wherein said touch pad issubstantially coplanar with said planar front surface.
 46. The controlstructure of claim 36, wherein said touch pad is disposed in a planeparallel to and above the plane of said planar front surface.
 47. Asystem for controlling power from a source to a load, comprising, incombination: (a) a cover plate that has a front surface with arectangular opening; (b) a touch pad behind said rectangular openinghaving an accessible continuous surface area for providing a signal inresponse to pressure applied anywhere along said accessible continuoussurface, the signal having at least one characteristic which is afunction of the actual location on the area of said accessiblecontinuous surface to which said pressure is applied; (c) circuit meansto adjust the power provided from said source to said load in accordancewith said signal, wherein said circuit means includes an electronicallyadjustable voltage dividing means; (d) a plurality of verticallyarranged markers printed on said touch pad to serve as scale indicator;(e) a plurality of status indicators coupled to said circuit means forilluminating respective discrete locations on said touch pad which lieon a line along the length of said touch pad and in a predeterminedalignment with respective ones of said printed markers and beingrespectively illuminated adjacent the position on said touch pad atwhich said touch pad is touched by an operator; (f) a small marker atthe bottom of said touch pad and in the center of the width of saidtouch pad, the control electronics operable to toggle said load whensaid touch pad is touched at the location of said small marker; and (g)at least a first status indicator connected to said control electronicsand positioned to illuminate said small marker and when said touch padis touched at said small marker to turn off said load.
 48. The controlstructure of claim 47, wherein said control structure is a wall boxstructure adapted for mounting on a wall.
 49. The system of claim 47,wherein said accessible continuous surface area of said touch pad isrectangular in shape.
 50. The system of claim 49, wherein saidaccessible continuous surface area of said touch pad has a height ofabout 4 to about 6 times its width.
 51. The system claim 50, whereinsaid rectangular shape has a height of about 5 times its width.
 52. Thesystem of claim 50, wherein said rectangular shape has a height of abouttwice its width.
 53. The system of claim 47, wherein the plurality ofstatus indicators comprise a plurality of LEDs.
 54. The system of claim53, wherein said plurality of LEDs consist of at least 7 blue LEDs. 55.The system of claim 53, wherein said discrete locations illuminated bysaid plurality of LEDs are disposed along one vertical edge of saidtouch pad.
 56. The system of claim 53, wherein said discrete locationsare vertically disposed along the center of the width of said touch padand wherein said LEDs are blue LEDs.
 57. The system of claim 47, furthercomprising: a second status indicator of color different from that ofsaid first status indicator, the second status indicator coupled to saidcontrol electronics and operable to illuminate said small marker whensaid touch screen is touched at any location.
 58. The system of claim53, wherein said LEDs are disposed beneath and are spaced from thebottom of said touch screen and further including light conductorsextending from each of said LEDs to respective ones of said discretelocations behind said touch screen.
 59. The system of claim 47, furthercomprising: an airgap switch; and an operator for said airgap switch,said operator including a lever having an end which extends onlysufficiently through said cover plate at the bottom of said rectangularopening to be gripped by a fingernail of an operator.
 60. The system ofclaim 47, wherein the area of said touch pad which is adjacent to thelocation of said marker is spaced from the lowermost one of thelocations of said plurality of status indicators by a distance to tendto prevent the touching by a finger of both the location of said markerdot and the location of said lowermost LED.
 61. The system of claim 60,wherein said control structure is a wall box structure adapted formounting on a wall.
 62. The system of claim 60, wherein said accessiblecontinuous surface area of said touch pad is rectangular in shape. 63.The system of claim 60, wherein said accessible continuous surface areaof said touch pad is rectangular in shape.
 64. The system of claim 60,wherein said accessible continuous surface area of said touch pad has aheight of about 4 to about 6 times its width.
 65. The system of claim60, further comprising: a second status indicator of color differentfrom that of said first status indicator, the second status indicatorcoupled to said control electronics and operable to illuminate saidsmall marker when said touch screen is touched at any location.
 66. Thesystem of claim 60, further comprising: an airgap switch; and anoperator for said airgap switch, said operator including a lever havingan end which extends only sufficiently through said cover plate at thebottom of said rectangular opening to be gripped by a fingernail of anoperator.
 67. The system of claim 60, wherein said area of said touchpad between said marker and said lowermost location of said plurality ofLEDs is deactivated and incapable of producing an output in response toa touch.
 68. The system of claim 60, wherein said small marker comprisesa small marker dot.
 69. A system for controlling power from a source toa load, comprising, in combination: (a) a cover plate that has a frontsurface with a rectangular opening; (b) a touch pad behind saidrectangular opening having an accessible continuous surface area forproviding a signal in response to pressure applied anywhere along saidarea, the signal having at least one characteristic which is a functionof the actual location on the area to which said pressure is applied;(c) circuit means to adjust the power provided from said source to saidload in accordance with said signal; (d) said rectangular opening havinga height about 4 to about 6 times its width; and (e) a shallow raisedarea at the bottom of said touch pad, wherein depression of said raisedarea operates an on/off operation of said circuit means.
 70. The systemof claim 69, wherein said rectangular opening has a height of about 5times its width.
 71. The system of claim 69, which further includes afirst status indicator positioned to illuminate said raised area.
 72. Acontrol structure for an electrical control system for producing avariable output electrical signal to an electrical load for controllablyvarying the output of said load, said control structure comprising: (a)an enclosed volume which contains control electronics; (b) a cover plateon one surface of said enclosed volume having a planar front surface andhaving a rectangular opening therein; (c) a transparent touch paddisposed in said rectangular opening and coupled to said controlelectronics and adapted to produce an output signal which is related tothe position within the area of said touch pad at which said touch padis touched by an operator; (d) a plurality of vertically arrangedmarkers printed on said touch pad to serve as scale indicator; and (e) aplurality of status indicators coupled to said control electronics forilluminating respective discrete locations on said touch pad which lieon a line along the length of said touch pad and in a predeterminedalignment with respective ones of said printed markers and beingrespectively illuminated adjacent the position on said touch pad atwhich said touch pad is touched by an operator.
 73. The controlstructure of claim 72, wherein said load is at least one dimmable lightsource.
 74. The control structure of claim 72, wherein said controlstructure is a wall box structure adapted for mounting on a wall. 75.The control structure of claim 72, wherein said touch pad issubstantially coplanar with said planar front surface.
 76. The controlstructure of claim 72, wherein said rectangular opening has a height ofabout 4 to about 6 times its width.
 77. The control structure of claim76, wherein said rectangular openings has a light of about 5 times itswidth.
 78. The control structure of claim 72, wherein said rectangularopening is a designer-style opening having a height which is about twiceits width.
 79. The control structure of claim 72, wherein the pluralityof status indicators comprise a plurality of LEDs.
 80. The controlstructure of claim 79, wherein said plurality of LEDs consist of atleast 7 blue LEDs.
 81. The control structure of claim 79, wherein saiddiscrete locations illuminated by said plurality of LEDs are disposedalong one vertical edge of said touch pad.
 82. The control structure ofclaim 79, wherein said discrete locations are vertically disposed alongthe center of the width of said touch pad and wherein said LEDs are blueLEDs.
 83. The control structure of claim 79, wherein said LEDs extendthrough said touch screen at said discrete locations.
 84. The controlstructure of claim 79, wherein said LEDs are disposed beneath and arespaced from the bottom of said touch screen and further including lightconductors extending from each of said LEDs to respective ones of saiddiscrete locations behind said touch screen.
 85. The control structureof claim 72, further comprising: an airgap switch in said enclosedvolume; and an operator for said airgap switch, said operator includinga lever having an end which extends only sufficiently through said coverplate at the bottom of said rectangular opening to be gripped by thefingernail of an operator.
 86. A control structure for an electricalcontrol system for producing a variable output electrical signal to anelectrical load for controllably varying the output of said load, saidcontrol structure comprising: (a) an enclosed volume which containscontrol electronics; (b) a cover plate on one surface of said enclosedvolume having a planar front surface and having a rectangular openingtherein; (c) a touch pad disposed in said rectangular opening andcoupled to said control electronics and adapted to produce an outputsignal which is related to the position within the area of said touchpad at which said touch pad is touched by an operator; (d) a pluralityof status indicators coupled to said control electronics forilluminating respective discrete locations on said touch pad which lieon a line along the length of said touch pad; and (e) and an audiocircuit coupled to said touch pad for producing an audible sound inresponse to the touching of said touch pad and the illumination of anyof said plurality of status indicators.
 87. The control structure ofclaim 86, wherein said control structure is a wall box structure adaptedfor mounting on a wall.
 88. The control structure of claim 86, whereinsaid rectangular opening has a height of about 4 to about 6 times itswidth.
 89. The control structure of claim 86, wherein the plurality ofstatus indicators comprise a plurality of LEDs.
 90. The controlstructure of claim 89, wherein said plurality of LEDs consist of atleast 7 blue LEDs.
 91. The control structure of claim 89, wherein saiddiscrete locations illuminated by said plurality of LEDs are disposedalong one vertical edge of said touch pad.
 92. The control structure ofclaim 89, wherein said discrete locations are vertically disposed alongthe center of the width of said touch pad and wherein said LEDs are blueLEDs.
 93. The control structure of claim 89, wherein said LEDs extendthrough said touch screen at said discrete locations.
 94. The controlstructure of claim 89, wherein said LEDs are disposed beneath and arespaced from the bottom of said touch screen and further including lightconductors extending from each of said LEDs to respective ones of saiddiscrete locations behind said touch screen.
 95. The control structureof claim 86, further comprising: an airgap switch in said enclosedvolume; and an operator for the airgap switch, said operator including alever having an end which extends only sufficiently through said coverplate at the bottom of said rectangular opening to be gripped by thefingernail of an operator.
 96. The control structure of claim 89, whichfurther includes delay means coupled to said audio circuit for delayingthe production of said audible sound for a predetermined time followingthe illumination of an LED.